T76s10

iTrader: (6)

ok so i ported my 317's and this is the first porting i have ever done. these are on a twin turbo lq4. i havent driven it yet so i dont know how well they will work but i want some feedback. one of my questions is, how far can you port the exhaust until you will run into waterjacket or cracking problems? i ported my exhaust ports almost as big as the gaskets and i see alot of people leave them kinda oval. are their different ways to port heads for turbo, nitrous, or NA? also i didnt really port the intakes much because they matched the gaskets pretty well so i just smoothed the castings off. heres some pics

ported exhaust ports on left, and unported on the right


all ported


and heres some 706's i ported

bww3588

iTrader: (49)

Looks good. The intake side takes a little more finesse as the gaskets are a little big. Just keep the basic shape and take down the rough casting. Blend the bowl to the runner and give the valve guide boss a knife edge.

bww3588

iTrader: (49)

Don't be afraid to take the casting bump down all the way and expose the rocker bolt hole. Just make sure you use a good sealant on the rocker bolts or you will have a small vacuum leak.

Blackpanther99

iTrader: (8)

I cant give an advise as far as porting goes but that looks nice.

farmington

iTrader: (14)

going to kill the exhaust gas velocity with that shape. Hate to say it, but I think you have ruined those heads

Fred Flintstone

iTrader: (1)

I argee with farmington, those are pretty much junk now. You should have went with
a d-shaped port. Should have searched head port shapes on here before doing any
porting. https://ls1tech.com/forums/generatio...6k-beware.html https://ls1tech.com/forums/generatio...-can-help.html

Not trying to be a butthole, just my .02

bww3588

iTrader: (49)

They may not be perfect, but I'll bet 10:1they out flow stock heads.

Grr

iTrader: (2)

there is really no restriction in the upper half of the port, you will gain basically nothing for the work you did as you didnt port around the valve seat, which is about the only spot that matters.

Also moving the floor of the port down to the gasket basically ruined those heads, IMHO you will make the same power or LESS than if you wouldnt have touched them at all

Your work looks good though, nice and smooth, FWIW

Grr

iTrader: (2)

Aside from that, I have personally taken completely stock 317 heads to around 800whp, so this was likely a giant waste of time

T76s10

iTrader: (6)

Thanks for the input guys. I never researched about the D shape and wish i would have. I focused more on the smoothing and no bumps and i think for three most part i did a good job on that. I should have blended the stem area allot better. Well we will see how they do when i start running the truck. The turbos are fairly small so the spool can't be terrible but only time will tell. Worst comes to worst I'll buy another used set and port them right.

T76s10

iTrader: (6)

Ive got tough skin so you guys don't need to sugar coat anything lol. If i messed up oh well atleast i learned and tried to do it myself.

gMAG

iTrader: (1)

Port the ceilings, but not so much the floors.
Valve guide area could use some.
Short-side radius, if it hasn't been done.
Behind the seat.
The exit, into your manifold/exhaust, should be smaller than the manifold.

gMAG

iTrader: (1)

I agree. The porting may not be AI, or TSP, but it sure beats a stock head.
There's a good thread going on by "AGearHeadForLife". He has several videos on YT, which are in his signature.
Otherwise, he can be found on YT "LS1 Head Porting".

anheuserbusch08

iTrader: (11)

Work. On the chambers u did good but a wee too much on the exhaust. If u want pictures of some for reference text me I have plenty of cylinder heads I've done 8325974079

T76s10

iTrader: (6)

What's the short side radius? I'll check out those threads

gMAG

iTrader: (1)

This is in picture #4 of your orig post, where you see the exhaust valve...then the valve seat area turns (arch/radius) and becomes the floor of the exhaust runner.
Where the turn is, is the short-side radius. The opposite of this would be the turn on the ceiling, which is longer.
Likewise for the intakes.
This is discussed in those videos.
Here's the link to his porting thread on LS1Tech...
https://ls1tech.com/forums/generatio...-can-help.html

T76s10

iTrader: (6)

thats alot of really good info. i didnt have plans to fully port these heads and get too out of hand with it because i didnt want to risk messing them up really bad because their my good set. i have two other sets like the 706's and 862's laying around that i ported the same way just for some practice. if these do end up making things worse then ill go through that video on that guys post you linked and do a diff set of 317's the right way.

gMAG

iTrader: (1)

I'm gonna have at it, shortly.
Because I have 806s, there isn't alot of worry, because there are folks selling these for $50.
Good luck with your porting.

64post

iTrader: (5)

Got that right! So little is gained by hogging out ports like that, GM engineers did the work for you with the stock shape. If you want bang for your buck, work on the bowls and guide boss, that's where the restriction is. Blend the bowls to the valve seats, remove swirl step and lay down/streamlne the guide bosses so the incoming charge doesn't hit a wall of restriction. Those heads are practice heads now.

wilfredes

going to kill the exhaust gas velocity with that shape.